Turbine blade copying machine



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United States Patent 3,027,814 TURBINE BLADE COPYING MACHINE Oscar Schnellmann, Zurich-Oerlikon, Switzerland, as-

signor to Gottfried Wachtberger vorm. Erich Franke, Maschinenfabrik, Heusenstamm, near Offenbach (Main), Germany, a firm Filed July 2, 1959, Ser. No. 824,617 Claims priority, application Switzerland July 11, 1958 3 Claims. (Cl. 90-243) The hitherto usual manner of producing turbine blades on the conventional copying machines presents a number of difiiculties which render the making of the blades costly and time consuming. Economy and rationalization combined with a high degree of precision and accuracy, however, are the outstanding requirements which must be observed in production. No grooves must be allowed to form when the profiles are being machined since the stringent requirements as to the weight of the blades call for a particularly perfect finish and high accuracy.

Various methods in'the production of turbine blades are known, such as by shaping after copying upon suitably modified shaping machines, or by copying milling machines, or by forming lathes in the rotation method. Other methods are grinding in the rotation method, or in accordance with cam diagrams and the like. In all these known cases comparatively long times for machining must be allowed without thereby ensuring the quality of the surfaces which would be required. The life of the grinding wheels, in the case of rotation grinding, is very short, and another drawback lies in that when grinding the blades in accordance with cam diagrams, an economic grinding of the inner profiles is only possible if the curves in these profiles are sufiiciently large. Besides, all turbine blade grinding machines which have been known up to the present operate after the conventional copy grinding method in which even the slightest wear on the grinding wheels affects the accuracy of the profiles to be ground. Subsequent finishing may improve the appearance of the blade but not its accuracy. These known machines operate according to the indirect copying method in which the shape of the tool depends largely on the shape of the part to be copied so that inaccuracies in the transfer of the profiles are possible. It is further usual to build machines of this type with coupled hydraulic or mechanical multi-stage drives so that all units have to be set to rest together whenever an exchange of the tool or of the work piece becomes necessary which affects the output of the machines very considerably.

In view of the high temperatures to which turbine blades are subjected, materials of great heat resistance are used, lately for instance a material called Nimonic, which is a hard metal containing about 80 to 90 percent of nickel. Materials of this class are hard to work on and while for this reason the finishing operations are normaly done by grinding, the first operations in the shaping of the blade profiles should preferably be carried out by means of cutting tools for which reason a machining allowance of one to three millimeters is usually provided.

The present invention refers to a one or multi-stage turbine blade copying machine in which each unit, in the case of a multi-stage machine, is independent of the other or others. In one of its more important aspects the invention consists in that arbitrarily a copying tool support or a grinding head with a swivelling copying roller is attached to a longitudinally movable and radially turnabie control element which is preferably in the shape of a horizontally disposed column which, notwithstanding this horizontal position, will hereinafter be referred to as column. It must be understood, however, that a vertical column may be provided if the construction of the machine allows for such. The rectilinear movement of the said column in its longitudinal direction serves to carry out the shaping or grinding stroke, while its radial swinging movement serves for the lateral feed of the tool or tools during the copying operation. The mutual vertical adjustment of the respective copying tools together with the copying roller for the approach of the tool toward the blade to be operated upon, with an additional tool lift by raising the copying roller as by means of a differential piston, is initiated by electro-hydraulic means by which the entire cycle of operations is controlled in order to enable a steady automatic flow of operations.

A preferred embodiment of the machine in accordance with the invention consist of a plurality of self-contained copying units for shaping the profiles of one or two blades per unit, whereby the machine may be designed as a oneor twostage machine with a common hydraulic and cooling means installation. Its main object is a more economic and uniform production of the turbine blade profiles, particularly of Nimonic-alloys or other hard materials, such as are used in the gears of aeroengines for instance. In the case of small series production the templates from which the turbine blades are copied, may be made of suitable synthetic or the like material, since the working pressure of the copying roller can be regulated as desired, which offers particularly economic advantages in the production of such small series.

The accompanying and largely diagrammatic drawings illustrate a machine in accordance with the invention by way of example.

In these drawings,

FIG. 1 is a side view of the machine,

FIG. 2 is a front view of the machine shown in FIG. 1,

FIG. 3 shows the front view of a multiple-stage copying machine with three copying units and a common hydraulic control.

FIG. 4 is a section through a complete unit with its shaping tool in the position of rest,

FIG. 5 is a longitudinal section through a copying unit with its shaping tool and copying roller in working position and FIG. 6 a similar view of the same unit with the shaping tool raised and the copying roller in its return position.

FIG. 7 is a cross section through the radial feed driving means.

FIG. 8 shows a cross section through the control means for the limitation of the working stroke.

FIG. 9 is a longitudinal section through the copying unit with a groove milling device for machining the foot grooves of the blades.

FIG. 10 is a section through the unit similar to FIG. 9 with a grinding device for grinding the blade profiles.

FIG. 11 diagrammatically illustrates the movement of the copying tool for inside copying, and

FIG. 12 the same for outside copying the blades, while FIG. 13 is a diagram of the inside copying movements of the tool on two blades in one operation.

FIG. 14 illustrates the hydraulic diagram for the automatic working cycle of a copying unit, while finally FIG. 15 is a horizontal section through the copying slide.

As illustrated in FIGS. 1 to 14 the machine, in its major parts, consists of the machine bed or standard 1 and the copying unit or units 2. Arranged within or upon the machine bed is the hydraulic installation which is indicated by the numeral 3, also the circulating pump 4 for the hydraulic fluid, the cooling equipment 5 and the electro-hydraulic controls denominated at 6. The machine bed may be designed for one or several copying units whereby the combined hydraulic installation 3 and circulating pump 4 including the cooling means 5 may serve for either one unit only or commonly for all.

Mounted on the machine bed 1 is the casing 7 of the copying unit as shown in FIG. 4, as also the ground plate -8 with the copying or master template 9 of the blade profile attached to it, and the clamp 10 for the blade to be operated upon. The special profile of the template 9 is somewhat larger in its length at both sides than the length of the turbine blade itself, in order to provide sufiicient room for the copying roller to run out. Arranged within the casing 7 and so as to be movable in longitudinal and radial direction is the horizontally disposed column 13, within which a cylinder 14 is fixed in position, wherein a piston 15 is adapted to reciprocate. This piston is rigidly held in a cover 16 by means of a nut 17. The cover 16 is screwed to the casing 7 by means of screws 18. It is provided with two channels 19 and 13' through which the pressure medium, usually oil, is able to pass so that, according to which of these channels is under pressure, the piston 15 is acted upon on either on its right or left side in order to move the column to the fore or to the aft as required.

Provided in the casing 7 is a longitudinal groove 20 in which a rack 21 is positioned so as to be capable of longitudinal movement. The said rack 21 is held by means of a projection 23 in a' circular notch 22 of the column 13 so that, when the column moves lengthways, the rack 21 is caused to join in the movement and to also move in the same direction. During this movement it meshes with a pinion 24 as will be seen from FIG. 8, which pinion is fixed to the shaft 25 of the control disc 26, which is provided with control earns 27 for the limitation of the stroke of the column 13. During their swinging movement the control cams 27 actuate the electric switch which, on its part, actuates the electro-hydraulic control valve (FIG. 1), whereby the required stroke of the column 13 becomes adjusted in conformity with the length of the copying stroke.

Also fixed to the shaft 25 is an eccentric 30 which actuates the pump 31, preferably a piston pump, for the central lubrication system of the copying unit. In FIG. 4 the arrangement of the piston pump 31 together with its oil pressure conduits 32, 33 and 34 is diagrammatically illustrated. FIG. 7 shows the control for the radial movement of the column 13 for the cross feed in the progress of copying.

Provided at the front of the casing 7 is a guide ring 35 which is turnably held in a box 36 (FIG. 4). Two ball or roller bearings 38 and 38 are carried on two pins 37, 37' extending inwardly from the ring 35 in mutually opposite direction (FIG. 7). The column 13 is provided along the whole of its length with guide surfaces 39 and 39 so that, when the ring 35 turns, column 13 will also turn owing to the ball bearings 38 and 38' being in contact with these surfaces. Mounted in the lower part of the box 36 is a piston 40 which is formed along its upper portion as a rack 41. Ring 35 is formed at its lower part with a toothed segment 42 which causes the ring 35 to tum on the piston being acted upon by pressure from the oil chambers 43 or 43'. In this way the speed of the piston and, consequently, the radial movement of the column 13 can be adapted to the cross feed of the copying tool or tools. Further on the guide ring 35 and adjustably fitted to the upper part thereof are two abutments 44 and 44' which, during the oscillating movement of the ring 35, alternately actuate an electric contact member 45 and thereby enable the hydraulic reverse of the piston 40.

At the forward end of the column 13 the copying slide 46 is vertically movable in guides 13 (FIG. 15). It moves in preferably hardened guides 97' and 97" in which it can be accurately adjusted by wedges 98 and 98. Journalled in this copying slide 46 is a shaft 47 (FIG. 4) and, capable of rocking movement thereon, the block 48 for supporting the copying roller 12. Also fitted within the copying slide 46 is a piston 49. The cylinder within which this piston is adapted to move, is closed at its top by a cover 50. Another piston 51 is adapted to reciprocate in a cylinder 54, which is rigidly attached to the column 13. When pressure is applied to the piston 51 in the chamber 52 the copying slide is moved downwardly until the copying roller 12 comes to bear on the template 9, while pressure exerted on the piston 51 in chamber 53 will return the slide into its upper position as shown in FIG. 4.

Mounted at the front face of the copying slide 46 by means of a bolt 57 is the exchangeable tool holder 55 for the shaping steel 56 which is clamped thereto over the bevel wheels 58 and 58' by a knurled hand plug 59. In FIG. 4 the copying slide is shown in its position of rest in which it is held partly by the pressure of the oil in the chamber '53 and partly by the chain 60 and spring 61. FIG. 5 shows the parts in their working position, the copying stroke having the direction indicated by the arrow a in that figure. Piston 51 is pressed downwardly by the constant pressure of the oil in chamber 52 until the copying roller 12 comes to bear on the template 9. In this working position the piston 49 is not acted upon, so that the holder 48 for the copying roller bearsfirmly against the abutment 60'. The spring 61 serves to equalize the pressure which is set up by the "block or holder 48. When the column 13 moves lengthways in the direction of its axis, the copying roller 12 is pressed under constant pressure against the copying template 9, whereby the copying tool 56 carries out synchronous movements along the blade 11 and thus produces the corresponding shape of the blade. I p

During the return motion of the .column 13 in the direction b in FIG. 6, piston 49 becomes acted upon by pressure through the conduit 62 so as to press the block or holder 48 downwardly through a certain distance which is marked 0 in the figure. The diameter of piston 49 is somewhat larger than the diameter of piston 51, so that by the pressure difference on the two pistons the copying tool 56 becomes lifted likewise by the amount 0, whereby the wear on the tool is reduced while at the same time the lateral feed can take place over the piston 40 during the return movement of the column 13. FIGS. 11 and 12 illustrate the turning movement of the copying tool 56 inside and outside of the turbine blade to be copied. FIG. 13 diagrammatically indicates the procedure on two blades simultaneously by the movement of the tool 56.

FIG. 14 diagrammatically illustrates the hydraulic control of a copying unit in accordance with the invention. The oil is conveyed from the container 62 by a pump 63 via a check valve 64 into the pressure regulating valve 65, from which it passes partly through the reversing valve 66 to the piston 51 of the copying slide of one unit, and partly to the difierential piston 49 for the lifting of the copying tool 56 in the return motion of the column 13. The control of the piston 49 during the return of the column takes place over the electro-magnetic or solenoid valve 67. The oil then passes from the check valve 64 over the electro-magnetic valve 68, the reversing valve 69 and the pressure regulating valve 71 to the piston 40 (FIG. 7) for the turning movement of the copying unit. Another pressure conduit via the control valve 71 and the solenoid valve 29 to the cylinder 14 and piston 15, whereby the oil is returned over the throttle valve 72 of the stroke speed adjustment into the oil container 62.

FIG. 9 illustrates in a diagrammatic way the copying slide 46 as equipped with a groove milling cutter 76 instead of the shaping tool 56 just referred to. For the purpose of milling the groove into the foot or the head of the blade a corresponding template may be used. The copying roller 73 is turnable on a short-shaft 74 in the block or holder 75 which is adapted to rock about the shaft 47 similar to the aforedescribed block 48. When this arrangement is used, the longitudinal, movement of the column 13 is set to rest and its radial or turning movement by means of the piston 40 only is applied. The milling cutter 76 on shaft 77 is driven by a motor 83 over the gear wheels 78, 79, 80, 81, and 82, which are positioned in a vertically adjustable gear box 84, and may be adjusted in its position of height by means of the screw spindle 85 which is provided with a graduated scale head 86 so that the shaft of the milling cutter 76 and that of the copying roller can always be held on the same level. The vertical approach and the return of the copying slide 46 is effected over the piston 51.

In FIG. the copying slide 46 is shown to be provided with a grinding device instead of the copying tool equipment heretofore described; the copying roller 12 and its holder 48, however, being maintained. The grinding wheel 87 is carried in a vertically slidable tubular holder 88. The adjusting spindle 89 is provided with two different screw threads, of which the thread 90 has only about half the pitch of the thread 90. The purpose of this is when trimming the grinding wheel by means of the diamond 91 as by screwing the scale knob 92, the holder 88 can be adjusted by an analogous amount downwardly in order to ensure the height of the grinding wheel being the same as that of the copying roller 12. The grinding wheel 87 is driven by means of compressed air or the cooling medium passing through a pipe 93 and a passage 94 to a turbine 95 which is coaxial with the grinding wheel 87 on a shaft 96 in rigid connection therewith.

The operation of the machine is as follows: The work piece, namely a turbine blade 11, is held in the machine by the clamp 10 opposite the template 9. A longitudinal movement of the column 13 to which the copying slide with its copying tool is attached so as to be capable of vertical movement thereon, starts the copying movement. When the tool 56 is to be replaced by another, the entire holder 55 has to be exchanged, so that the exact position of depth of the tool 56 can be maintained without thereby atfecting the output of the machine. Piston 51 presses the copying slide 46 down until the roller 12 contacts the template 9, the lower face of the copying roller thereby taking the same position of height as the cutting point of the shaping tool 56. Thus, when the column 13 moves in its longitudinal direction, the cutting tool 56 will carry out the movements prescribed by the curves on the template and transmit them directly to the turbine blade 11. Inasmuch as the turbine blade requires a cross feed of the copying tool, this is caused by a radial movement of the column 13 by the feed piston 40, whereby an image of the template 9 is transmitted to the turbine blade 11. During the return of the column 13 the pressure on the difierential piston 49 increases and lifts the tool 56 off the work. The length of the movement of the column 13 in accordance with the blade 11 can be set by the adjustment cams 27, while its radial movement in accordance with the width of the blade is adjustable by means of the cams 44 and 44'. These cams are designed to actuate the electric control means for the operation of the machine.

Instead of the cutting or shaping tool 56 a milling unit 84 with a groove cutter 76, for instance, may be fitted to the copying slide, which is preferably driven by a separate motor 83. Such milling tool is particularly serviceable for cutting the foot grooves of the blades 11 in order to provide a run-out for the shaping tool. The width of the groove may be as required, the normal width being three to ten millimeters. The axis of the copying roller 73, in this case, is positioned parallel to the axis of the column 13, and the longitudinal movement of the latter is used for setting the distance between the grooves of the turbine blade. For this operation only the radial feed of the column 13 by the piston 40 need be actuated.

The aforesaid copying means may also be exchanged against a grinding device which is likewise fitted to the copying slide 46 and is provided with a grinding wheel 87 which may be driven by compressed air or by the cooling medium through the turbine to which the grinding wheel may be directly coupled. The copying roller, in this case, is arranged parallel to the shaping tool unit. By means of the grinding device the turbine blades 11 are ground down to the allowances specified in each particular case. Feed in both directions, straight and radial, is the same as with the use of a shaping tool.

The device in accordance with the invention renders the simultaneous operation of several units at a comparatively small consumption of space on a common machine bed possible. Also in this case various copying methods may be employed arbitrarily on the same machine such as shaping, milling or grinding and by using the same templates for all operations.

What I claim is:

1. A turbine blade copying machine, comprising a machine bed adapted for mounting thereupon at least one copying unit, a clamping device for a turbine blade and spacedly aligned therewith, holding means for a template the shape of which, except for its length, corresponding exactly with that of said turbine blade to be machined, said copying unit comprising a housing, a ram horizontally supported therein, hydraulic means for axially reciprocating said ram and hydraulic means for radially moving said ram about its axis, a vertically movable slide carrying a tool head, said slide being mounted on one end of said ram, a lever pivotally mounted on a horizontal shaft disposed at the lower end of said slide, a copying roller aligned with the tool and rotatably mounted on a shaft arranged in parallel, spaced relation to said pivoting shaft on said pivoting lever, means resiliently urging said pivoting lever against an abutment disposed on said slide, a hydraulically operated first piston slidingly arranged within a cylinder fastened to the end of said ram, a piston rod extending from said first piston the end of which being fastened to said slide for moving it up and down, a second hydraulically operated piston having a larger diameter than said first piston slidingly arranged within a cylinder disposed on said slide above the free end of said pivoting lever adapted for pivoting said pivoting lever and thereby raising said slide and tool a predetermined distance against the force of the first piston while said copying roller is contacting said template on the return stroke of said ram, and electro-hydraulic means for controlling the movements of said different hydraulically operated means.

2. A turbine blade copying machine, comprising a machine bed adapted for mounting thereupon at least one copying unit, a clamping device for a turbine blade and spacedly aligned therewith, holding means for a template the shape of which, except for its length, corresponding exactly with that of said turbine blade to be machined, said copying unit comprising a housing, a hollow ram of substantially circular cross section horizontally supported in said housing, a hydraulically operated cylinder coaxially and fixedly arranged at one end within said ram, a piston within said cylinder having a piston rod rigidly connected with the housing of said copying unit, hydraulic channels extending through said piston rod communicating with the cylinder spaces on both sides of said piston being alternatingly pressurized for reciprocating said ram, a hydraulic cylinder arranged below said ram within said housing of the copying unit the axis of which lying at a right angle to the axis of said ram, a piston sliding in said last named cylinder for rotating said ram the middle portion of which forming a rack meshing with teeth provided on said ram, a vertically movable slide carrying a tool head, said slide being mounted on one end of said ram, a lever pivotally mounted on a horizontal shaft disposed at the lower end of said slide, a copying roller aligned with the tool and rotatably mounted on a shaft arranged in parallel, spaced relation to said pivoting shaft on said pivoting lever, means resiliently urging said pivoting lever against an abutment disposed on said slide, a hydraulically operated first piston slidingly arranged within a cylinder fastened to the end of said ram, a piston rod extending from said first piston the end' of which being fastened to said slide for moving it up and down, a second hydraulically operated piston having a larger diameter than said first piston slidingly arranged within a cylinder disposed on said slide above the free end of said pivoting lever adapted for pivoting said pivoting lever and thereby raising said slide and tool a predetermined distance against the force of the first piston while said copying roller is contacting said template on the return stroke of said ram, and electro-hydraulic means for controlling the movements of said different hydraulically operated means.

3. A turbinetblade copying machine as claimed in claim 1, in which means are provided for controlling the working cycle of the longitudinal and radial movements of the copying tools by a fluid medium such as compressed air.

References Cited in the file of this patent UNITED STATES PATENTS 

